In many fields of industries such as foods, machinery, chemistry, etc., the labels printed with various indications such as marks, letters, patterns, etc., for example, the labels having such indications printed on one side of the support base and provided with an adhesive layer on the other side are attached to the products or their packages to facilitate the process management. A typical instance of such labeling technology is the management system making use of the bar code labels. In this bar code management system, information on various matters such as the state of production of the products, cost, etc., is mechanically read from the bar code labels to control the production, process of sale, etc.
The ordinary bar code labels, however, are stuck to the adherends through the medium of an adhesive layer composed of an acrylic resin or such, so that this adhesive layer might be decomposed or evaporated under the harsh temperature conditions of over 350° C., and therefore this labeling system was incapable of application in the fields of industries involving high-temperature treatments such as ceramic, iron and glass industries, for example, in the manufacturing process of cathode-ray tubes for television which includes the steps of sealing and annealing at 400 to 600° C., or in the process of working of metal products after hot rolling or hot molding.
In order to improve heat resistance of the adhesive layer, studies have been pursued for compounding a silicone resin and an inorganic material such as metal powder (JP-A-7-334088, JP-A-11-52861, etc.). These attempts, however, were unable to clear the problem that the adhesive force at high temperatures was not always satisfactory because of insufficient heat resistance of the silicone resin used as matrix.